"Damien Broderick" <thespike@earthlink.net> writes:
>> The "chemical replicators" are mechanical. Peptide synthesis in
>> ribosomes is mechanosynthetic....
>> The problem, I think, is a continuing belief in vitalism, although I'm
>> sure Smalley would stringently deny that.
>
> My sense is that Smalley's response might be that each of these enzymatic
> syntheses is a one-off, a specially designed (`designed') gadget that
> functions in a specific co-evolved ambient. That might not readily
> generalize to a universal assembler, or even to multi-purpose nanoscale
> tools. Not vitalism: complexity and deep history.

It depends on what you mean by "universal assembler". The a small
collection of living organisms forms a fully self contained system
capable of turning sunlight and raw feedstocks into a very wide
variety of products. One might say that all the components that do
this are "one-offs", but so what? No one said such a system needed to
use ONE machine tool for everything. Indeed, it would be rather
unexpected if it could.

The question is not whether we can build some sort of mechanosynthetic
catalyst that could produce absolutely anything -- that's a strawman
and almost certainly impossible.

The weak question is whether or not we can produce a set of tools
capable of atomically precise assembly of a wide variety of useful
products including themselves. That question has an obvious answer --
just look in the mirror.

The stronger question is whether or not we can produce a set of
mechanosynthetic tools capable of producing literally any molecular
configuration not at odds with the laws of physics. That remains a
more open question, but I think there is little doubt that we can
produce an extremely wide variety of interesting molecular targets --
including a vast array of molecular robotics and atomically precise
molecular electronics -- that are of substantial interest.